Trajectory of muscle strength and functional performance after ACLR

Michael Girdwood

Introduction

Kambhampati & Vaishya, 2019

Background

Limitations of previous reviews:

  • Focus on single muscle only (Ardern 2009; Lisee 2019; Moloney 2014)
  • Graft comparisons only (Dauty 2005; Xergia 2011)
  • Isometric contractions only (Lisee 2019)
  • Lack of quantitative meta-analysis (Petersen 2014)
  • Not comparing to uninjured controls (Abrams 2014)

Background

More recent reviews

  • Focused on matched case-control comparisons citing confounding issues of the contralateral limb (Tayfur 2021; Brown 2021)
    • Much lower pool of evidence available than within-person comparisons

Comparator limb

Contralateral (uninjured) limb

Pros ✅

  • affected by same environmental factors as ACL limb
  • most biologically similar
  • ‘internal control’

Cons ❌

  • affected by same environmental factors as ACL limb
  • ‘moving target’ - improves with rehabilitation or becomes deconditioned
  • affected by bilateral CNS changes

Comparator limb

Pre-injury contralateral limb

Pros ✅

  • overcomes post-injury exposures
  • compares to an uninjured state

Cons ❌

  • pre-injury exposures? (i.e. weakness)
  • often not available clinically (unless collected immediately post-injury (e.g. EPIC (Wellsandt, 2017))

Comparator limb

Uninured (healthy) control limb

Pros ✅

  • comparison to healthy uninjured people
  • potentially unbiased comparator

Cons ❌

  • requires normalisation & matching (e.g. sex, age)

  • relevant population data not always available (e.g. sport/activity specific)

  • introduces biological varaibiltiy to comparisons

Background

Functional Performance

  • No summary since Abrams, 2014 SR 10 years ago
  • Hop tests widely collected in research and clinically, and recommended in all guidelines (Whittaker, 2022; Andrade 2020)

Aims

How does muscle strength and funcional performance change over time after ACLR

  1. compared within-person (i.e. to the uninjured contralateral limb)
  2. compared between-person (i.e. to uninjured healthy populations)

Methods

A group of systematic Reviews with meta analysis

  1. Quadriceps and hamstring strength
  2. Hop performance
  3. Hip and lower leg strength

Databases: MEDLINE, EMBASE, CINAHL, Scopus, Cochrane CENTRAL, SPORTDiscus

Inclusion criteria: primary ACL injury, aged 18-40 years, with a quantitative measure of muscle strength or hop performance

Methodological Quality Assessed on domains outlined by Cochrane Collaboration

Comparison:

  • to the contralateral leg
  • to an uninjured control group

Methods

A group of systematic Reviews with meta analysis

  1. Quadriceps and hamstring strength
  2. Hop performance
  3. Hip and lower leg strength

Additional Criteria:

  • Published from 2010 onwards
  • Minimum sample size of n=50

Effects - Ratio of Means

Effects - Ratio of Means

\[\begin{equation} RoM = \frac{90Nm}{100Nm} \end{equation}\]



Example: ACL Side compared to the contralateral side

ROM = 0.9 95%CI[0.85-0.95]

= ACL side is 0.9x weaker than the contralateral side

= 10% deficit in ACL side strength

The problem

The solution!

Longitudinal/multivariate meta-analysis

  • Ishak et al 2007, Clinical Trials

  • Trikalinos & Olkin 2012, Clinical Trials

  • Cheung 2019, Neuropsychol Rev

  • Mueskiwa et al 2016, PLOS ONE

The solution!

Longitudinal/multivariate Meta-Analysis

Allow multiple (correlated) pieces of information from the same study to be included in a meta-analysis

flowchart TD
  A{Crossley et al} --> B(3 months)
  A--> C(6 months)
  A--> D(12 months)
  • timepoints
    • same people measured over time
  • outcomes
    • same people measured for linked or correlated outcomes (e.g. separate measure for anxiety and depression)
  • comparisons
    • same control groups for different comparators

Traditional “Univariate” Meta-Analysis

  • “2-Level”

  • Random effects for

    • studies (between study heterogeneity)
    • individuals
flowchart TD
  A[Meta-analysis] --> B(Study 1)
  A--> C(Study 2)
  B--> D(i)
  B--> E(iii)
  B--> F(iii)
  C--> G(i)
  C--> H(iii)
  C--> I(iii)

Longitudinal/multivariate meta-analysis

  • “3-Level”

  • Random effects for

    • studies
    • timepoints (or some other clustering variable)
    • individuals
flowchart TD
  A[Meta-analysis] <--> B(Study 1)
  A<--> C(Study 2)
  B--> D(T0)
  B--> E(T6)
  D--> F(i)
  D--> G(ii)
  D--> H(iii)
  E--> I(i)
  E--> J(ii)
  E--> K(iii)
  C--> L(T0)
  C--> M(T6)
  L--> N(i)
  L--> O(ii)
  L--> P(iii)
  M--> Q(i)
  M--> R(ii)
  M--> S(iii)

Data Analysis

  • Mixed-effects meta-analysis with a REML estimator using metafor package.
  • Quadriceps and hamstring, separated by contraction type:
    • Slow concentric ≤120°/s
    • Fast concentric >120°/s
    • Isometric


Random effects:

(timepoint | cohort)

  • timepoints, nested within cohorts

Fixed effect: timepoint

  • linear, log linear, polynomial, 3-knot spline and 4-knot spline

Robust variance estimation methods using clubSandwich package 🥪

Results

  • 233 studies 🥵
  • 🇦🇺 🇬🇧 🇺🇸 🇮🇷 🇯🇵 🇹🇷 🇧🇷 🇳🇴 🇰🇷 🇸🇪 🇨🇭 🇸🇮 🇳🇱 🇬🇷 🇵🇱 🇦🇹 🇮🇹 🇩🇪 🇹🇼 🇳🇴 🇸🇬 🇶🇦 🇨🇳 🇪🇸 🇨🇦 🇩🇰 🇧🇦 🇹🇭
  • 31,234 ACLR participants; 3049 controls; (40% women)
  • Mean age: 18-38 years, median 25
  • Mean BMI: 21.3 to 28.4 kg/m2; median 24.2
  • Most common timepoints:
    • 3 months (k=35)
    • 6 months (k=88)
    • 12 months (k=59)

Knee extensors (quadriceps)

Slow concentric knee extensor

Fast concentric knee extensor

Isometric knee extensor

Knee flexors (hamstrings)

Slow concentric knee flexor

Fast Concentric knee flexor

Isometric knee flexor

Graft Type

Extensor grafts ~ Quads Strength

Flexor grafts ~ Hamstring Strength

Exploratory Analysis

Exploratory Analysis



  • Several papers (n=27) report comparisons for
    • within-person &
    • between-person
  • Bivariate analysis of pairs of studies

Is comparing to the contralateral limb equivalent to comparing
to uninjured controls

Between-person deficits were 1.53x greater than within person (95%CI 1.15 to 2.19)

Hop Performance

Hop Performance

  • 6 most commonly reported hop tests:
    • single forward
    • triple forward
    • triple crossover
    • 6m timed
    • side hop
    • vertical hop

Hop Performance

Relationship between different hops

Beyond the thigh muscles: Hip and lower leg muscle strength after ACLR

Why might the hip and calf muscles be important?

  • important contributions to frontal plane knee stablity Maniar, 2022
  • potential link between impaired hip strength and worse knee OA outcomes Hall, 2017
  • gastrocnemius also contributes to knee stability and compression forces Mokhtarzadeh, 2013
  • hip and calf muscle strengthening included in rehabilitation trials Culvenor 2023; Beard 1998; Hohman 2011
  • hip muscle weakness seen in many other knee conditions (e.g. PFJ pain, PT, non-traumatic OA)

Methods

Systematic Review with Meta Analysis

Same methodology as reviews thigh muscle strength and hop performance



Differences to previous reviews

Inclusion criteria: primary ACL injury at age 18-40 with a quantitative measure of hip or lower leg (calf) strength

Exclusion criteria: No restriction on sample size or publication year

Overview

  • 28 studies 🇦🇺 🇬🇧 🇺🇸 🇮🇷 🇯🇵 🇩🇪 🇹🇷 🇧🇷 🇳🇴 🇰🇷

  • 1103 ACL injured (all except 12 reconstructed) + 1145 controls

  • Mean age ranging from 19 to 38 years

  • Most timepoints between 7-12 months post ACL surgery

  • Limited information on activity levels

    • n=5 athletes
    • n=4 ‘recreationally active’
    • n=6 with Tegner scores (range 5-7)

Comparison within person

Comparison with uninjured controls

Discussion


No consistent or widespread weakness of the hip or calf muscles after ACL injury

  • Despite all studies included showing significant quadriceps and hamstring weakness when measured


Limitations

  • Low sample size especially for hip IR, flexion, soleus and dorsiflexors

  • Variability and heterogeneity

  • Very low certainty evidence

Thank you ++